Manufacture of steel armor-plate, &amp;c., with a hardened face.



No. 774,959. 4, 2 S a 2 Patented November 15, 1904.

TOL-MI-E JOHN TRESIDDER,

OF SHEFFIELD,INGLAN D.

MANUFACTURE OF STEEL ARMOR-PLATE, &c., WlTH A HARDENED FACE.

SPECIFICATION forming part oflgetters Patent No. 774,959,- dated November 15, 1904;

Application filed nly 17, 1903.

To all whom, it may concern:

Be it known that I, .TOLMIE JOHN TRESID- .DER, a subject of the King of. Great Britain and Ireland, residing at Atlas Iron and Steel 5 Works, Shefiield, in the county of York, England, have invented certain new and useful ,Impror 'ements in the Manufacture of Steel Armor-Plates or other Plates of Steel with a -Hardened Face, of which the following is a specification. v 4

' The object of thisinvention is to provide steel plates for armor or other purposes with hardened faces and with tough backs which will not crack and which can be manufactured in asnaprem reliable manner.

It is presumed for the purpose of description that the plates to be produced are armorplates; but it is to be understood that the invention is applicable to the production of facei hardened steel plates for any other, purpose;-

Armor-plates with a hardened face as hitherto made may be divided into two main kinds, th'e first kind being those which, although simple to manufacture, havea body part or back which is not sufiiciently tough to enable the plates tobearheavy blows or artillery fire without cracking, and the second kind being those which,although theyhave a body part or back which is not liable to crack under heavy 3 blows or artillery fire, yet are at certain stages of their manufacture extremely delicate and require great care and precaution in manipulation, and even then it-is not unusual to have failures necessitating the remelting of the metal; l Moreover, the roughness of the rolled surface of plates which,like those of the hereinbefore-referred-to second 'kind, contain a comparatively large proportion of nickel is such that in many cases they have to be sur- 4 faced in a planing-machine. The difiiculties of manufacture of plates of the said second kind also increase as the thickness of the plates deer-eases.

- Acc'ording'tn this in iention Plates .can be.

manufacturedwitli all-the facility of manufacture of the aforesaid first kind and without limitation as,to thickness and at the same time wanin hjgli bailistic resistance and immu-' nity from cracking hitherto obtainable only by' a complicated and expensive process.-

Serial No. 166,013. (No niodel.)

According to this ins ention a steel is" produced having such a composition that when a plate made therefrom is treated as herein-' after described it can Have iinl larted to it a fibrous structure which will remain undete'ri orated, or even be improved when the plate is heated armature; a High temperature and *suddenlycouiedrtheiinventfonnmiutfififofi 'e'ration'sffi fi'efeifiafter described, for restoring to the metal its fibrous characterafter it it in the cementation-furnace.

steel having the following compositionnamely, iron, carbon, manganese, nickel, and tungsten-4n 0:15am the following proportion'sdn each ten thousandiiaits, by'weight, of thesteel mixture; carbon, from twenty-eight to tbilttyo-two'wparts',by weight; manganese,

nickel from two hundred and twenty-five to two h undredand fifty parts, by weight; tungfrom twenty-five to thirty parts, by weight; '7

sten, from twenty-eight to thirty-two parts, by

silicon and the usual impurities kept within the low limits usual in high-class steels.

. ceeding in manufacturing the steel having the abovecomposition. The char e, consisting of about one-half good hematite or Swedish pig-iron and the other half good pure steelscrap, is melted on the Siemens hearth until the impurities have been eliminated and the carbon, as judged by fracture of aspoon sample,;is under one-fifth per cent, and then weight, the remainder being iron with a little Thefo llo wingis the preferred way of prov nickel, preferably in the form of rondelle'sof metallic nickel, is thrown into the bath and stirred therein. When this isthoroughlyin:

.corporated, which will-usually be in about ten minutes, red-hot ferromanganese is added in Such quantity asexperience shows;will'after.

allowing for the ineyitable loss leavethedesired percentage of manganese. }'When.,the

said. ferromanganese has been well-stirredin,

the tungsten is added, preferably in the'con- No allowanceneed be made for loss of tungsten; As soon as the jferrotungsten has had ditionofred hotiferrotungsten containing about one thirdtungsten and two-thirds iron.

5 has necessarily been temporarily deprived of is tapped into a ladle and cast into an ingot,

The ingot thus produced is of such a character ture has to be given to it) and after bending.

that before being reheated itcan be laid down and allowed to cool without being liable to spontaneous disintegration; but, if desired, it can while still hot be at once taken to the forging-press or rolling-mills to be forged or rolled into plates without any special precautions being necessary, and if ordinary steps be taken for removing scale the surface will not require to be machined; but if it e desired to machine it machining can be donewith facility. The plate having been pressed or rolled to the desired thickness is allowed to become cold, and rough-machining can, if desired, be done at this stage. It is next placed in a cementing-furnace, where one side is supercarburized, which may be done in any of the usual ways, and preferably to a fairly high degreesay so as to analyze about one and one-half per cent. of carbon at the face. The plate must not be allowed to cool in the cementation-furnace, but must be taken out hot and be immediately subjected to one of the following treatments, viz:(a) Rerolling or reforging while ata temperature of about 1,800 Fahrenheit. In this case the original rolling or forging should be stopped while the plate -is still about one-third thicker than is ultimately required. (6) Quenching in oil from a temperature of 1,600 to 1,7 00 Fahrenheit. (0) Chilling with a water douche from a temperature of about 1,550 to 1,650 Fahrenheit.

Of these treatments the last (a) is recommended for plates under four inches thick, and the second (b) for plates over that thickness, while the first, (a,) which involves risk of loss of carbon from the face, is best restricted to plates which are too thin to be conveniently carburized at their-finished thickness.

Fahrenheit (or more if considerable curvato shape, if required, (allowing for the warping that may be expected from the final process,) permitting the plate to cool gradually. It should then be machined to finished dimensions and subjected to a repetition of either of the treatments hereinbefore mentioned under 6 and 0, after which the final treatment may be applied, which consists in heating the plate uniformly throughout to from 1,450 to 1,550 Fahrenheit and chilling it with a water douche. r

' Test-scrap for fracture should be left attached to the plate as usual, and the fracture should be examined after the second of the hereinbefo're-mentioned treatments 6 or a. At this stage the non-cemented portion should The next process is to uniformly heat the plate to about l,100-

As in neither of the hereinbefore-described treatments is it required to have the face and back of the plate simultaneously at different temperatures, very thin faces a pgh cks' -such as are suitable, for instance, in making safes and the like can be produced.

aving now particularly described and ascertained the nature of the said invention and in what manner the same is to be performed, I declare that what I claim is 1. The manufacture of steel plates by. first producing an ingot of steel composed of iron, carbon, manganese, nickel and tungstenTand for ging, or rolling; that cementing, orsupercarburizing, the face and cooling, and afterward restoring the fibrous character to the uncemented part; all substantially as hereinbefore described. f

2. The manufacture of steel plates by first making an ingot of steel composed of iron, carbon, manganese, nickel and tungsten, reforging or rolling, supercarburizing the face and cooling, reheating and gradually cooling, and finally heating and face-hardening; all substantially as hereinbefore described. 1

3. The'manufaeture of steel plates by first making an ingot of steel composed of iron, 7

carbon, manganese, nickel and tungsten, and then, while hot, forging, or rolling it, and allowing it to cool, then cementing, or supercarburi zing. one side and, quickly cooling,

then uniformly heating the plate, and cooling 5 gradually, and after machining to the finished dimensions, reheating and quenching till a good fibrous condition of the uncemented part is obtained; and finally uniformly heating and chilling; all substantially as hereinbefore de 110 scribed.

:In testimony whereof I aifix my signature 1n presence of two witnesses.

. :roLMIE JOHN TRESIDDER.

Witnesses;

EDWARD CHARLES HAMMOND, WILLIAM Gemin REYNOLDS. I

l tes with hard 

